Railway track jacking devices



Aug. 5, 1969 J. K. STEWART RAILW AY TRACK JACKING DEVICES Filed July 25. 1966 ATTaRNEI S US. Cl. 104-7 3 Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with a track lifting jack capable of constantly bearing the weight of the track through a magnetic clamp for a track surfacing operation regardless of whether large or small lifts are required, the flux density available at the magnetic clamp being controlled as a function of the loading on the jack.

This invention relates to a railroad track jacking device suitable for use with a railroad track maintenance of way vehicle, for example a tamping machine. Machines of this type today are usually fitted with jacks to jack the track to a desired level and consolidate the ballast under the jacked track, by tamping it.

I have previously proposed the jacking of a track by means of an electromagnet, that is, I utilize an electromagnet to engage each of the rails of railroad track so as to grip the rails and apply a jacking force through electromagnet to lift the track. It will be immediately apparent that the actuation of the electromagnets each time a jacking operation is to be performed and the deenergization of the magnets after making the required lift, leads to the maintenance operation being split into a series of steps, as indeed is the case with presently available machines, thereby reducing the production rate of the machine. Therefore I advocate the constant energization of the magnets so as to constantly bear the weight of the track. However, the force which has to be applied to the track to jack it to a required height varies with the condition of the track. For example, during a surfacing operation, only a relatively small jacking force is necessary if track depression from the desired height is small and local and, consequently, only a small amount of track needs to be lifted through a small height to achieve correction. On the other hand, where the track has been badly worn and the track depression is considerable, then the force required to correct the track is relatively large and approaches a force approximately equal to that necessary for an out-of-face lift, since a large amount of track will have to be lifted through a considerable height.

It will be seen that it is necessary for the rail engaging magnets to have an available flux density capable of causing the magnet to lift a rail for the most extreme condition likely to occur. The constant application of this high value of flux density to the rails by the magnets causes great difliculties where the instantaneous required flux density is relatively small, i.e. where the lift is to be slight and local, in other words a condition where a great deal less flux density would be sufficient. The result of maintaining the maximum required flux density at all times, causes the magnet to take on the proportions of a large weight at times when much less than maximum flux density is required to perform the necessary instantaneous lift. This is due to frictional forces thus created and the vehicle has to push the magnet along the track with the result that a severe load is applied to the vehicle.

Applicant has found that if he can control the flux density available at the magnet to be in proportion to the required jacking force, that is to say if suflicient flux density is available to lift the track as required without the magnet breakr 3,459,135 Patented Aug. 5, 1969 ing contact with the rail, if only sufficient extra flux density is applied to account for natural losses and working conditions, then the magnet can be kept in constant use without breaking free from; the rail throughout a complete working operation of many tamping cycles. Indeed it is envisaged that contact need not be broken with the rail throughout an entire working shift.

Accordingly, applicant provides a track jacking device which comprises rail engaging magnetic means; jack means adapted to jack the track; sensing means operatively connected with said jack and adapted to sense the loading on the jack; and flux control means operatively connected to the magnetic member and to the sensing means and responsive to the sensing means whereby to control the flux density at the magnetic means in proportional relation to the loading on the jack.

Preferably the jack means is connected to the magnetic means.

In a preferred construction the jack means is a hydraulic piston and cylinder arrangement and the sensing means is a pressure sensitive transducer located in the cylinder.

The following is a description by way of example of certain embodiments according to the present invention, reference being had to the accompanying drawings in which:

FIGURE 1 shows diagrammatically, the arrangement of a device in accordance with the present invention;

FIGURE 2. shows the magnet at the point of contact with the rail, looking along the direction of the track; and

FIGURE 3 is a diagrammatic detail of the magnet and jack arrangement.

Referring now to FIGURES l and 2 of the drawings:

An electromagnet 10 adapted to engage a rail of the track, located on a truss 11, which forms part of a jack means, the truss being in the form of a lever pivotally mounted on a bearing 12 on a front wheel W of the jacking vehicle V. A hydraulic piston and cylinder arrangement 13 also mounted on the vehicle, and forming the remainder of the jack means, engages on the one hand, the end of the truss 11 remote from the magnet 10 and on the other hand, a bearing 13b on the rear wheel W2. Within the cylinder 14 of the piston and cylinder arrangement there is located a pressure sensitive transducer 15 connected to a suitable controller 16 which controls the source 17 of flux for the electromagnet 10. The present invention could suitably be used with a surveying system such as described in my United States Patent No. 3,144; 834 (British patent application 23,398/62). In that system an infrared transmitter located remotely from the jacking vehicle projects an infrared beam towards the receiver mounted on the rear of a jacking vehicle, a sensor in contact with the track, and in the nature of a shadow board, is located adjacent the jacking point at the front of the vehicle between transmitter and receiver and when the shadow board sensor sinks into a hollow caused by the dip in a track the receiver is exposed to the transmitted beam. The received signal causes, through the medium of a circuit including a servo valve, hydraulic fluid under pressure to be admitted to a jacking cylinder to cause the track to be jacked until such time as the shadow board is lifted with the track and again shadows the receiver from the transmitted beam. Suitably also, the present invention could be used with such a system when modified by having the servo valve operate to cause the jacking element to operate in the opposite sense when the receiver is obscured from the transmitter by the shadow element. A simple measuring device would then be coupled with the receiver and adapted to control the servo valve in one direction or another in accordance with the degree of intensity of the received beam.

With such a modified system the present invention could be used so that the magnet 10 could be kept in lifting contact with the rail virtually throughout the whole of a working shift. v

The magnet and jack means illustrated in FIGURE 1 will of course be duplicated for the second rail of the track and be operated independently.

In operation the electromagnet receives its energy from source 17 and saturates the rail in the immediate vicinity of the magnet 10.

Where a suitable surveying device indicates that the track is hollowed the piston and cylinder arrangement 13 is operated to lift the track by pulling down on one end of the truss 11, causing it to pivot about its pivot point 12 and by means of the magnet 10 lift the track until the surveying device indicates that the track is being lifted to the correct height. At this point the track would be tamped by tamping heads in the jacking vehicle V.

If insutficient fiux density is provided to the magnet 10, as soon as the jacking operation commences, it will merely part company with the rail, thus flux density at the magnet must at all times be sufficient to provide the necessary gripping force to lift the rail Without separating therefrom. As the jacking operation commences, the transducer 15 immediately senses the pressure conditions within the cylinder 14 and relates these conditions to the controller 16 which governs the source 17 in such a fashion that Where a great lift is required and the pressure in the cylinder 14 increases through the jacking operation, the flux density available at the magnet 10 will keep pace with the demand, or load, on the jack and will increase as the load or demand on the jack increases and will decrease as the load or demand on the jack decreases. In this fashion the inventor maintains the flux density at the magnet 10 at a level sufficient to only just lift the track without parting company therefrom, of course natural losses being allowed for.

Since the lifting effort of the magnet 10 is always balanced by the weight of the track to be lifted there is a minimum amount of difference weight to be pushed along the track by the vehicle whilst the magnet is in continual operation.

In FIGURE 3 there is shown an alternative arrangement of the present invention in which the jack cylinder 14 is mounted directly above the magnet 10 and the magnet is connected to the piston rod 14p. The jack 14 is rigidly connected to the truss 11 which in this instance provides a rigid extension of the frame of the vehicle so that the actual lifting of the rail is counter-balanced by the weight of the vehicle, the front wheels vW. forming the pivot point of the system. Again, a transducer 15 is provided in the cylinder and is connected with the controller 16 which controls the source 17 of flux for the electromagnet 10.

What I claim as my invention is:

1. A track jacking device comprising rail engaging magnet means; jack means including a hydraulic piston and cylinder arrangement operatively connected to said magnet means to jack the track; a pressure sensitive transducer located in said cylinder and adapted to sense the loading onthe jack means; and flux control means operatively connected to the magnet means and tothe pressure sensitive transducer and adapted to be responsive to the pressure sensitive transducer to control the available'fiux density for the magnet means in proportional relation to the loading on thejack means. v

2. Apparatus as claimed in claim 1 in which the jack means is directly connected to the magnet means.

3. A track jacking device comprising rail engaging magnet means; jack means operatively connected tosaid magnet means and adapted to jack the track; sensing means connected with said jack and adapted to sense the loading on the jack; and flux control means connected to the magnet member and to the sensing means and responsive to the sensing means whereby to control the flux density at the magnet means in proportional relation to the loading on the jack.

References Cited UNITED STATES PATENTS 903,552 11/1'908 Eastwood et a1 29465.5 1,915,566 6/1933 Younghusband 29465.5 2,046,310 7/ 1936 Billner lO5--77 2,628,122 2/1953 Collins et al 294-655 3,032,363 5/1962 Clayborne 294-655 794,086 7/1905 Eastwood 335291 3,196,320 7/1965 Manting 335291 3,247,912 4/1966 Reynolds 317123 FOREIGN PATENTS 1,419,536 10/1'965 France.

ARTHUR L. LA POINT, Primary Examiner RICHARD A. BERTSCH, Assistant Examiner 

